Question

The time required to finish a test in normally distributed with a mean of 40 minutes and a standard deviation of 8 minutes. What is the probability that a student chosen at random will finish the test in more than 48 minutes?

Answer 1

Here we have = 40, = 8

The time required to finish a test is normally distributed.

Here we need to find,

p ( x > 48 )

= p ( z > 1 )

= 1 - p ( z 1 )

= 1 - 0.8413 -------------- (using excel formula " =norm.s.dist(1,1)" )

= 0.1587

The probability that a student chosen at random will finish the test in more than 48 minutes is 0.1587.